Operating head for welding machines and the like



March 1,4, 1950 M. M. sEELoFF OPERATING HEAD FOR WELDING MACHINES AND THE LIKE Filed June 26. 1946 2 Sheets-Sheet l ig la.

||||||||||||||| infn- Il.-- 1 f grvuIz/wtofr/ MELVIN M. SEELOFF March 14, 1950 OPERATING HEAD FOR WELDING MACHINES AND THE LIKE Filed June 26, 1946 M. M. sEl-:LoFF `2,500,876

2 sheets-snaai 2 Patented Mar. 14, 195.0

OPERATING Fon 4WELDING; MACHINES AND THE LIKE Melvin RL SeeloiyWarren, Ohio, assignor to The' Taylor-Winfield Corporation, Warren, Ohio, a

corporation of ,Ohio

ApplicationJ une 26,11946, Serial No. 679,333';

fClaims.` 1

This; invention-relates to. electric resistance...` Welding apparatus;` particularlyV of the 'spoti or'` press. welding; type, and gis.: concerned. moref vspe-- ciiicallyl with.. improved.; apparatus ffor. actuatingand controlling the. actuation of". tliemovable electrode-or-headi off the-,welding machine... In'` machines of thisi.characten, it; hasf heretofore been". proposedito associate; with. the electrodefor headfmoving meansfapparatus: for governing the` initiarwelding forcee applied; and. further.; additional means: tozabruptlyincreasethe weldingA forceftaefiect a forgingmction in precisely timed: relation invthe weldingtcycle. A- system.` of this nature; utilizing a hylzlraulicfiiuid;cylinderv is dis-'- closed" and.` claimed=LiIrUnited States. Patent No. 2,392,296 wherein: the-increased; orf'forging pres-, sure, is eiected; byf abruptlyu. diverting.4 a moving columnpf hydraailic;fiuid;into the outer.y end .off

the. cylinder.;v in; suchymanner; that: the` kinetic energy inherent 'in lthe ,moving column: ofz'luidz. iss converted and?.A utiliaedlxtol providel thevincreasedf welding force.

In thdsystem of `theabove.y mentioned patent the hydraulic fluid.; is, of. course, also employed. .to effect OpeningandclOSing of the welding electrodes. ofthe welding machine. for* insertion and removalV of Work. pieces as` willnbe understood;. In 4welding.'machinesot the subject' character-it. has. also been proposed to provide an-.arrange ment. whereby thefmotvabl'e: electrode of the as= semblyY has arelativelyshort normal operating. stroke. to:.lessen:.machine1 wearxandto.` keep thev time required for completionfof successive .Weld-4 ingpcycles to. a. ,minimum;. and'. to provide. a. fur:- therarrangement to. greatlypincrease the openfing'. stroke of'. theffmovable electrodezinstantly at. the: will` o! the operator to facilitate dressing-and change of electrodes; insertion of bulky work pieces, etc.M Thefpresent inventionprovides. a simple andeconomical arrangement for incorporatingv'this additional desirable operatingV feature in a spot or press Welder-of the general' character iirst described.

Another objectlof the invention is the provision off an improvedlapparatus forcontrollingfthe` length4 of the normal operating'stroke of any electrode carrying head in an electric resist-ance spot or press welding' machine.

A further object of the invention isrthe provih sion of an improvedi'cont'rol system and circuit for a movable electrode carrying head ofr anvelec'- tric resistance welding `machine embodying appatatas-for providingfanormal-flength offY operating stroke andan increased length retraction stroke whichis-l instantly 4available-at the will of the-operator;

The. above'. andothenobjects and advantages` of theinvention willfbecomeapparent upon ccnsideration of the Afollowing# detailedspeciii'cation4 and the accompanying' drawing wherein there is.`

disclosed a preferred embodiment of. the 'inven-f tion.

Inf: the drawing.:

Figurev 1A isa. combined mechanical and schematic .linediagram representationfof a Weldingimachine constructed in. accordanceM with the principles; of the invention; and

Figures 2 and,3* are fragmentary mechanical views of aportion of the apparatusoftiligurea1.f

Reference; numerah lil designates a bracket.-

which extends outwardlyl from the principal frame or housing ofgthecomplete Welding ma-` chine, not shown, andpin accordance with usual.v

practice aunormallyf iixed electrode lll is suittably carriedby-Such: frame -or lnousing. Slide,- ably: mounted. in the. bracket. Illfis a: quilll.y I2I carryingat its lowergend a welding-electrode I3, and beinggconnectednat its-.upper end Withavv rodleading to a piston `hl'housed inV cylinder: l5.:

Hydraulicfluid` isadmitted.; to theupper end. of

cylinder |.5f through' ,conduit |61 and to the` lower endr'of the cylinder through conduit. Il. trodesv ll manner.` tothe secondaryY of a welding transformerv I8.l

Hydraulic. 'uid pressurefis furnished; by1 a@ motor driven pump f |-9 having. its.-4 inlet connected. with a reservoirV 20; anditsgoutlet connected with a conduit A2|.-

conduit 2l, a second port connected'with aconduit.. Hifby means ofconduit 23, a vthird port connected with .conduit;|.'|.by,. means-oipconduit. 24, and a fourth-` portconnected to anreturn con.-`

duit 25;.which leadsbaclc to. the reservoir., 2U.

|5 against movement in either direction.

Asshown in. Figurefl, upon: the. solenoid, 2:1 being energized and the1=core offvalve 221ibeing.;

consequently moved: toeth'e left',f; conduit v2ll is?. connected withv,.conduit;.y 23. while conduit..A I7' ist connected with. returnconduit 25 sol that fluidVl flows;` into the: lupper -end of v cylinder l 5 and ,outy of. thef lower endthereofN whereby?, the.- piston.

thereinl moves downwardlyto,` close the electrodes.

. Il andfl3'.

(Loni'iectingv withconduit'y 23 is. aeconduitt; leading, to .the -returnvconduitI 25and' interposed" in conduit. 28.. is anfopen valve:` Zai-arranged to be'V closedy byv a. solenoid *80,* andfan adjustable pres-` surey relief :valve 3l Thus;v during` normal@ opera )Elec--y and; I3 are: connected in the usual:`

I provide a spool-type .controle valve 2A2Lhaving: an inlet` port connected` withVA tion of the welding machine and the closure of the electrodes onto the work after energization of solenoid 21 the welding force applied is determined by the setting of the relief valve 3|, it being understood that after stoppage of down- Ward movement of the piston in cylinder I5 the fluid delivered by the pump I9 is' returned by way of conduit 28, relief valve 3| and conduit 25.

A second pressure relief valve 32, normally set for higher pressure than relief valve 3|, is provided to discharge the output of pump I9 into return conduit 25 upon centering of valve 22 and the vconsequent blocking of conduit 2|. When solenoid 21 is de-energized and solenoid 26 is energized the valve core is moved full to the right, connecting conduit 2| with conduit 24 and conduit 23 with conduit 25 whereby the piston I4 will be moved upwardly and the electrodes moved apart. A third relief Valve 33 interconnects the conduit 24 with the return conduit 25 so that upon the piston I4 being moved to its uppermost position the output of pump I9 can be diverted to the reservoir 2U without unnecessarily high pressures being developed in the cylinder.

To adjustably limit the length of normal operating stroke of the slide I2 I provide a limit Switch 35 having an operating arm 36 and adapted to control the hydraulic system in the manner to be hereinafter described and by means of the control circuit also to be hereinafter described. Switch 35 is mounted on a carrier 31 mounted for vertical sliding adjustment in a slot 38 formed in the bracket I0. A manually engageable screw-threaded clamping member 39 is provided to lock the switch in adjustment position and on the face of the bracket I I may provide a scale 40 to visually indicate the length of stroke alotted to the slide I2 during normal operation of the welding machine. The operating arm 36 of the switch 35 is arranged to be actuated by a member 4| (Figure 2) carried by the slide l2 and the arrangement is such that upon the slide I2 reaching a predetermined upper position as controlled by the location of the carrier 31 the switch 35 will be opened.

To control the apparatus thus' far described there is provided a control circuit including the line conductors 42 and 43 leading from a suitable source of alternating current, conventional type relays 44, 45, 46, 41 and 48, a single stage foot switch 49, a two stage foot switch 50, and a ratchet type of relay which is operative upon successive energizations to positively move the armature to alternate positions as will be understood. The nature of switch assembly 50 is such that upon manual actuation plunger A is first depressed followed automatically by plunger B. Upon release plunger B rst retracts, followed by plunger A to restore the assembly to the position shown.

The operating coil for relay 48 is in a circuit which may be traced from line Iconductor 43 through conductor 52, normally closed first-stage contactor 53 of switch 58, conductor 54, normally open contactor 55 of switch 49, conductor 56, normally closed contactor 51 of relay 46, conductor 58, and coil of relay 48 to line conductor 42. Thus upon actuation of switch 49 relay 48 is energized and the solenoid 21 is energized through the circuit-line conductor 42, conductor 59, solenoid 21, conductor 60, contactor 6| of relay 48, and conductor B2 to line conductor 43. This moves core of valve 22 to the left as shown in Figure 1 and fluid pressure is admitted to the` top of cylinder l5 to close the electrodes in the manner explained above. Coupled with conduit IE is a pressure responsive switch 63 arranged to clos'e a circuit comprised of conductors 34 and G5 upon proper welding force being applied between the electrodes. The primary winding of welding transformer I8 may be energized from the source comprising the conductors 42 and 43 under the control of apparatus shown schematically at B6 and such apparatus may be effective to connect the primary winding with the source for a predetermined interval of time following the closure of circuit 64-65 by switch 63. Welding current now begins to flow and to apply the increased or forging pressure above discussed solenoid 3D is now energized to abruptly block the circulation of the moving column of hydraulic fluid in the conduits 23 and 28 so that the inertia inherent in this moving column may be converted abruptly into increased pressure in the conduit I6. To effect such operation relay 44 is provided with a contactor 61 which connects the solenoid 30 across the line conductors 42, 43 upon energization of the coil of this relay. The energizing circuit for this coil may be traced from the line conductor 42 through said coil, conductors 68 and 64, switch 63, conductors 65 and 69, an adjustable time delay device to delay energization of coil 44 for a predetermined interval following initiation of flow of welding current, conductor 1|, a contactor 12 on relay 48, and conductor |52 to line conductor 43. Thus, simultaneously with the initiation of flow of welding current or at a delayed time with respect f thereto, solenoid 30 is energized to abruptly close valve 29 thereby effecting an increased or forging pressure in the welding electrodes.

The energizing circuit for the coil of relay 46 includes the switch 35 so that upon opening of this switch the coil of relay 46 is de-energized. Relay 46 normally controls the energization of the solenoid 26 through the circuit which may be traced from line conductor 42, solenoid 26, conductor 13, contactor 14, of relay 45, conductor 15, contactor 18 of relay 46, conductor 11, contactor 13 of relay 48, and conductor 62 to line conductor 43. Thus, during upward movement of the slide I2 as results from energization of solenoid 2B the switch 35 is operated to de-energize relay 48 thereby de-energizing solenoid 26, allowing the valve 22 to center to lock the piston I4 in its position attained at the time of actuation of switch 35. It should be observed that this energizing circuit requires the relay 48 to be deenergized and to provide a sufficient weld hold" time before the pressure is released from the electrodes and the electrodes opened (energization of solenoid 28) even though the foot switch 49 be held down. I insert time delayed contactor 1S in the conductor 53 to open the circuit for the coil of relay 48 at a predetermined time during the welding cycle and the operation of this contactor E8 is also such that it provides for the automatic retraction of the upper electrode I3 through its normal operating stroke as will be understood.

To provide for the full retraction of the upper electrode or head of the welding machine the apparatus now to be described is utilized. Such apparatus includes the ratchet relay 5 I, the operating coil of which is in a circuit traceable from conductors 43 and 52 through contactor 80 of part A of switch 50, conductor 8|, coil of relay 5|, and conductor 32 to line conductor 42. Therefore upon the switch 58 being actuated through its first.

stage, contactor 83 of relayl is closed to condition a circuit traceable from line conductor 43 throughthenormally closedfcontactor 8.4 of f oot switch 49, conductor 85, second-stage contactor 86 of switch 50, contactor 83, conductor 81, coil of relay 41, and conductor 88 to line conductor 42. Thus, upon the switch 50 being actuated through its second stage relay .41 is .energized and by meansof a contactor 89 on relay.41 the energizing circuitffor-solenoid 26 is bypassed around the contactorl of-relay .51 and the'solenoid 25 is again energized to continue the `upward movement of the slide I2 beyondthe point at which switch 35 is normally opened thereby providing for the full retraction of the slide. The switch 50 may now be released and because of the self-centering nature of lthescore in valve 22 the `welding head including the upper electrode I3 will remain in uppermost position. To bring the head back down to the top of its normal operating stroke I provide an energizing circuit for the relay 45 which is traceable from line conductor 43 through contactor 84, conductor 85, contactor 86, contactor 90 of ratchet relay I5, conductor 9I, contactor 92 of relay 46, coil of relay 45, and conductor 93 to line conductor 42. Switch 50 is now actuated and the coil of relay 5I is rst energized to open contactor 83 while closing contactor 90 and shortly thereafter the coil of relay 45 is energized by closure of contactor 86. Such actuation of relay 45 opens the energizing circuit for solenoid 26 by reason of contactor 14 and simultaneously effects the energization of solenoid 21 through the circuit-line conductor 42, solenoid 21, conductor 6U, conductor 94, contactor 95 of relay 45, contactor 16 of relay 46, conductor 11, conductor 18 of relay 48, and conductor 62 to line conductor 43. Downward movement of the slide continues automatically until proper position is reached to open switch 35 thereby (ie-energizing relay 46. The foot switch 50 may now be released and the system is in recycled condition for nor-mal welding operation through actuation of the foot switch 49. A holding contact 96 is provided for relay 48 to insure complete performance of a welding cycle operation even though the foot switch 49 is released immediately.

It should now be appreciated that I have provided an improved driving assembly for the movable head of an electric resistance welding machine which accomplishes the obj ects initially set out. Through the use of the principles of the invention I am enabled to provide a driving or operating assembly for the movable welding head of an electric resistance welding machine which requires a minimum of mechanical apparatus but which, nevertheless provides for completeness and nexibility in the operation and control of the welding head, including the desirable features of a short but adjustable normal operating stroke, or a long full retraction stroke at the will of the operator, as well as an increased or forging pressure applicable in precisely timed relation during the welding cycle. Such mechanical apparatus as is required in the system is moreover of a simple and dependable nature, requiring only more or less conventional components, and as such the same may be economically produced and serviced as will be understood.

The above specically described embodiment of the invention should be considered as illustrative only as obviously many changes may be made therein without departing from the spirit or scope of the invention. For example, while I have illustrated the invention as being applied to a spot Welder. .it Should vv.be Clearly .understood Vthat the principles 0f the invention` are equa11y; applicable to resistance Welders generally, including :butt Welders. Reference should therefore be had-Lto the appended Claims `in determining; the.. ksopeof the invention.

What'I claim-is:

.1. Iny electricresistance;Welding :apparatus hav, ing a movable head Carrying a .wielding electrode and ahvdraulccylinderfcr moving said head the combination of a four-way valve foron trolling the now of hydraulic nuid into opposite ends of said cylinder, saidvalve being oftheioen-- tering `type and thus operative to simultaneously block the flow of fluid outwardly of either end of said cylinder whereby said head may be locked in predetermined position along its path of travel, and adjustable means operative upon said head reaching a predetermined position along its retraction stroke to actuate said valve to said centering position.

2. In electric resistance welding apparatus having a movable head carrying a welding electrode and having a hydraulic cylinder for moving said head the combination of a four-way valve for controlling the ilow of fluid into and out of opposite ends of said cylinder whereby movement of said head may be controlled, a persistent source of hydraulic fluid pressure, a rst conduit con necting said valve with an end of said cylinder for supplying iiuid in a direction tending to apply welding force through said electrode, a second conduit connecting said valve with the opposite end of said cylinder, said valve being of the centering type whereby both of said conduits may be simultaneously blocked at said valve to lock the head in predetermined position, means to actuate said valve in opposite directions to eiect opposite movements of said head, control means operative in response to said head reaching a predetermined retraction position to interrupt actuation of said valve whereby said valve returns to centering position, a return conduit connected with said iirst conduit and having therein a pressure relief valve and a controlled blocking valve, and means to actuate said blocking valve at a predetermined time during a welding cycle.

3. Apparatus according to claim 2 further lncluding manually engageable control means to effect re-actuation of said valve after interruption by said first mentioned control means whereby said head may be further retracted along its full length of stroke afforded by said cylinder.

4. In electric resistance welding apparatus having a movable electrode carrying head and a hydraulic cylinder for moving said head in opposite directions and for applying welding force to said head the combination of conduit means to conduct hydraulic fluid into and out of opposite ends of said cylinder, adjustable means operative upon said head reaching a predetermined position along its retraction stroke to block said conduit means thereby locking hydraulic fluid in both ends of said cylinder to retain said head in a locked position, and manually controlled means to render inoperative said adjustable means whereby said head may be further retracted at the will of the operator.

5. In electric resistance welding apparatus having a movable slide carrying an electrode and a hydraulic cylinder for moving said slide the combination of a housing member movably supporting said slide, a limit switch, means adjustably mounting said limit switch on said housing member for adjustment along aline substantially parallel with movement of said slide, an operator for said limit switch carried by said slide, means to admit hydraulic fluid into one end of said cylinder while discharging fluid from the other end thereof whereby said slide may be moved in a retraction direction, and means operated by said limit switch to block said means to admit and discharge whereby retraction movement of said slide is automatically interrupted after which said slide is locked in the position attained.

6. Apparatus according to claim 5 further including manually controlled means to render said limit switch controlled means inoperative whereby said slide may be further retracted as desired. 15 Number MELVIN M. SEELOFF.

REFERENCES cnmi UNITED STATES PATENTS Number Name Date j 1,153,384 Heany Sept. 14, 1915 1,315,876 Southall Sept. 9, 1919 2,016,728 Sciaky Oct. 8, 1935 2,067,363 Waeschle Jan. 12, 1937 2,329,851 Platz Sept. 21, 1943 FOREIGN PATENTS Country Date 805,999 France Sept. 14, 1936 700,344 Germany Dec. 18, 1940 

